An old question, for which I could find absolutely NO reference on the internet for many years. Perhaps I wasn't looking in the right places, but I have no clue about its usage either.
Then I stumbled upon this article just now that actually happened to address the same premise. I tried to figure out myself as a function of context but my better judgement was to seek expert advice. So here goes.
In the following excerpt I found in an article:
Ricky: Yo player let me get some of that valium!
Albert: **** off these are for my back spasms.
Ricky: Okay fine then I will tell your girlfriend about last weekend.
Albert: Fine, here you go a**hole.
Ricky: Word.
What exactly does word mean at the end? What are its connotations? Thanks :)